Collaborative Construction of Polybenzoxazine Nanocomposite Coatings for Hydrophobic, Heat-Resistant, and Corrosion-Resistant Applications Using Functionalized Boron Nitride Nanosheets

To broaden the advanced applications of polybenzoxazine resin in the field of metal corrosion protection, main chain benzoxazine (BA-ddm) and diamine benzoxazine (Ph-hda) were first synthesized and then compounded to fabricate copolymer (PB5). Simultaneously, polyetheramine (PEA) grafted hexagonal boron nitride (h-BN) nanosheets (PEA- g -BNNS) were prepared by chemical exfoliation and surface modification through Lewis acid–base interaction. PEA- g -BNNS was subsequently blended with PB5 copolymer solution, followed by coating and thermal curing on the surface of tinplate to obtain PEA- g -BNNS/PBZ nanocomposite coatings. The structure and morphology of PBZ nanocomposite coatings were investigated by FTIR, XRD, 1 HNMR, and HRSEM. The hydrophilicity-hydrophobicity, thermal stability, and corrosion resistance of PBZ nanocomposite coatings were characterized through contact angle, TGA, and electrochemical tests. Microstructure characterization results of fillers and PBZ nanocomposite coatings verified the successful functionalization of PEA- g -BNNS and fabrication of PBZ nanocomposite coatings. The contact angle of PEA- g -BNNS/PBZ coatings reached up to 119.6°. The TGA test showed that the 2% PEA- g -BNNS/PBZ coating had excellent thermal stability. The electrochemical test showed that the PEA- g -BNNS/PBZ coating had good corrosion resistance. Among them, the 2% PEA- g -BNNS/PBZ coating exhibited the best anti-corrosion performance. Even when immersed in 3.5 wt.% NaCl solution for 20 days, the |Z| 0.01 Hz value remained 2.00 × 10 10 Ω cm 2 .